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3. Mutualistic nutrition
- Two organisms in close association.
- Both contribute to and benefit from relationship.
For example,
Rhizobium and Papilionaceae
- Rhizobium – nitrogen fixing bacteria
- Papilionaceae – a flowering plant, leguminous
- Nitrogen fixation
- Requires anaerobic conditions
- Catalysed by enzyme nitrogenise
- Uses energy in the form of ATP
Relationship
- Roots of Papilionaceae release hormones.
- Hormones attract Rhizobium.
- Rhizobium penetrates roots.
- Moves to cortex of root.
- Stimulates production of plant hormones such as auxin.
- Causes nodule of tissuse to from (composed of large amounts of Rhizobium).
- Rhizobium in nodule become Y-shaped (now called bacteroids).
- Leghaemoglobin surrounds bacteroids and absorbs any oxygen present.
- Provides anaerobic conditions needed for nitrogen fixation.
Benefits of relationship
- Rhizobium obtains supplies of carbohydrate from photosynthetic activity of Papilionaceae.
- Papilionaceae receive supply of ammonia from Rhizobium (process of nitrogen fixation) allows it to grow in nitrogen deficient soil.
4. Parasitic nutrition
- A parasite is an organism which lives in close association with another living organism, the host.
- The parasite is dependent upon the host for food and can cause the host harm.
- Endoparasites live inside their host while Ectoparasites live on the outside of their host.
For example,
Taenia Solium
- Pork tapeworm
- Endoparasite
- Primary host - man - adult stage attached to wall of small intestine.
- Secondary host - pig - larvae develop in muscular tissue of a pig.
Adaptations
- No mouth or alimentary canal.
- It absorbs digested food of host from all over body.
- It has tegument, thick outer covering made of protein and chitin to protect from acidic condition and action of digestive enzymes.
- It can live in low oxygen concentrations.
- It reduced nervous system and lack of sense organs.
- It produces large amounts of offspring
- It has suckers and hooks to attach to gut wall of host (scolex-head).
- Proglittides containing self fertilised eggs are excreted from host body in faeces and can be taken in by pigs.
Damage to humans
- Very little effect on healthy hosts except deprivation of food.
- In unhealthy hosts can causes abdominal pain, vomiting, constipation, loss of appetite and may become less resistant to other diseases.
Adaptations of Herbivores
- Upper incisors replaced by horny pad.
- Sideways movement of jaw allows grass to be cut by lower incisors and canines against horny pad.
- Roots of teeth open so can grow continually.
- Diastema, toothless gap between incisors and premolars for forming bolus.
- Premolars and molars all same height and flat allowing sideways movement of jaw.
Digestive System
- Four chambered stomach
- Grass fermented in rumen and reticulum by bacteria
- Food is regurgitated and rechewed- rumination
- Passes onto omasum and the abomasums
Adaptations of Carnivores
- Large pointed canine teeth which enables them to pierce the skin of and kill their prey.
- Their incisors are small that that of a ruminant and are used for nibbling meat of the bone.
- Their molars and premolars are sharp and act like scissor blades.
- Their jaws move up and down and not side to side they bite, cut and swallow food quickly so that another animal does not take it.
- They have carnassials teeth adapted for slicing.
- They have sharp hearing and eyesight and are fast and agile allowing them to hunt effectively for food.
That's the end of the topic!
Drafted by Bonnie (Biology)